Update at 3 p.m. ET. In its latest update, the National Hurricane Center says that tropical storm Isaac "could be near hurricane strength" when it reaches Haiti later today. That's a slightly more serious forecast from where we began the day.

Still, though, the tropical storm is packing a punch. The Hurricane Center says its maximum sustained winds are now about 50 mph and that there are gusts of up to 80 mph.

As for where Isaac is headed, it will likely blow over Cuba this weekend and then through the Florida Keys and South Florida. The latest projected path now puts it on a course to perhaps give Tampa — site of next week's Republican National Convention — at least a glancing blow. But Isaac looks to be headed more toward the Florida Panhandle, and the coasts of Alabama, Mississippi and perhaps Louisiana.

Eric Blake, a Hurricane Center forecaster, tells The Associated Press that Isaac could still "become a hurricane on Monday ... somewhere over the Gulf of Mexico."

The Federal Emergency Management Agency is urging people in the Keys and areas along the Gulf Coast that may be in Isaac's path to "get prepared."